Add back method CongestionController::GetTransportFeedbackObserver.

webrtc/modules/congestion_controller/include/congestion_controller.h

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 76 matching lines @@
   virtual void SignalNetworkState(NetworkState state);
   virtual void SetTransportOverhead(size_t transport_overhead_bytes_per_packet);
 
   virtual BitrateController* GetBitrateController() const;
   virtual RemoteBitrateEstimator* GetRemoteBitrateEstimator(
       bool send_side_bwe);
   virtual int64_t GetPacerQueuingDelayMs() const;
   // TODO(nisse): Delete this accessor function. The pacer should be
   // internal to the congestion controller.
   virtual PacedSender* pacer() { return pacer_.get(); }
+  virtual TransportFeedbackObserver* GetTransportFeedbackObserver() {
+    return this;
+  }
   RateLimiter* GetRetransmissionRateLimiter();
   void EnablePeriodicAlrProbing(bool enable);
 
   // SetAllocatedSendBitrateLimits sets bitrates limits imposed by send codec
   // settings.
   // |min_send_bitrate_bps| is the total minimum send bitrate required by all
   // sending streams.  This is the minimum bitrate the PacedSender will use.
   // Note that CongestionController::OnNetworkChanged can still be called with
   // a lower bitrate estimate.
   // |max_padding_bitrate_bps| is the max bitrate the send streams request for
@@ skipping 88 matching lines @@
   std::unique_ptr<DelayBasedBwe> delay_based_bwe_ GUARDED_BY(bwe_lock_);
 
   rtc::ThreadChecker worker_thread_checker_;
 
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(CongestionController);
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_CONGESTION_CONTROLLER_INCLUDE_CONGESTION_CONTROLLER_H_